Cells employ active measures to restrict infection by pathogens, even prior to responses from the innate and humoral immune defenses. In this context selective autophagy is activated upon pathogen induced membrane rupture to sequester and deliver membrane fragments and their pathogen contents for lysosomal degradation. Adenoviruses, which breach the endosome upon entry, escape this fate by penetrating into the cytosol prior to autophagosome sequestration of the ruptured endosome. We show that virus induced membrane damage is recognized through Galectin-8 and sequesters the autophagy receptors NDP52 and p62. We further show that a conserved PPxY motif in the viral membrane lytic protein VI is critical for efficient viral evasion of autophagic sequestration after endosomal lysis. Comparing the wildtype with a PPxY-mutant virus we show that depletion of Galectin-8 or suppression of autophagy in ATG5-/- MEFs rescues infectivity of the PPxY-mutant virus while depletion of the autophagy receptors NDP52, p62 has only minor effects. Furthermore we show that wildtype viruses exploit the autophagic machinery for efficient nuclear genome delivery and control autophagosome formation via the cellular ubiquitin ligase Nedd4.2 resulting in reduced antigenic presentation. Our data thus demonstrate that a short PPxY-peptide motif in the adenoviral capsid permits multi-layered viral control of autophagic processes during entry. Cells have developed surveillance systems to detect invading pathogens, e.g. when they damage the membrane upon cell entry. Cells respond to membrane damage by activating selective autophagy to target pathogens for lysosomal degradation and pathogen removal. In this manuscript we show that endosome penetrating adenoviruses also activate an autophagic response upon entry and that this involves Galectin-8 mediated membrane damage recognition similar to pathogenic bacteria. In contrast adenoviruses avoid degradation by escaping into the cytosol. We show that they possess a small virion encoded PPxY-peptide motif, which they use to divert the autophagic response of the cell. This motif sequesters the cellular ubiquitin ligase Nedd4.2 resulting in limited autophagosome formation, which prevents viral degradation and antigenic presentation and ensures efficient endosomal escape and nuclear transport.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections initiate in the bronchi of the upper respiratory tract and are able to disseminate to the lower respiratory tract, where infections can cause an acute respiratory distress syndrome with a high degree of mortality in elderly patients. We used reconstituted primary bronchial epithelia from adult and child donors to follow the SARS-CoV-2 infection dynamics. We show that, in epithelia from adult donors, infections initiate in multiciliated cells and spread within 24 to 48 h throughout the whole epithelia. Syncytia formed of ciliated and basal cells appeared at the apical side of the epithelia within 3 to 4 d and were released into the apical lumen, where they contributed to the transmittable virus dose. A small number of reconstituted epithelia were intrinsically more resistant to virus infection, limiting virus spread to different degrees. This phenotype was more frequent in epithelia derived from children versus adults and correlated with an accelerated release of type III interferon. Treatment of permissive adult epithelia with exogenous type III interferon restricted infection, while type III interferon gene knockout promoted infection. Furthermore, a transcript analysis revealed that the inflammatory response was specifically attenuated in children. Taken together, our findings suggest that apical syncytia formation is an underappreciated source of virus propagation for tissue or environmental dissemination, whereas a robust type III interferon response such as commonly seen in young donors restricted SARS-CoV-2 infection. Thus, the combination of interferon restriction and attenuated inflammatory response in children might explain the epidemiological observation of age-related susceptibility to COVID-19.

Since the beginning of the COVID-19 pandemic, different viral vector-based and mRNA vaccines directed against the SARS-CoV-2 “S” spike glycoprotein have been developed and have shown a good profile in terms of safety and efficacy. Nevertheless, an unbiased comparison of vaccination efficiency, including post-vaccination neutralizing activity, between the different vaccines remains largely unavailable. This study aimed to compare the efficacy of one mRNA (BNT162b2) and two non-replicating adenoviral vector vaccines (ChAdOx1 nCoV-19 and Sputnik V) in a cohort of 1120 vaccinated Palestinian individuals who received vaccines on an availability basis and which displayed a unique diversity of genetic characteristics. We assessed the level of anti-S antibodies and further determined the antibody neutralizing activity in 261 of those individuals vaccinated with BNT162b2a (121), ChAdOx1 (72) or Sputnik V (68). Our results showed no significant difference in the distribution of serum-neutralizing activity or S-antibody serum levels for the three groups of vaccines, proving equivalence in efficacy for the three vaccines under real-life conditions. In addition, none of the eight demographic parameters tested had an influence on vaccination efficacy. Regardless of the vaccine type, the vaccination campaign ultimately played a pivotal role in significantly reducing the morbidity and mortality associated with COVID-19 in Palestine.

Le cytomégalovirus humain (CMV) appartient à la sous-famille des Betaherpès virus. L’homme est son seul réservoir et il infecte 40 à 90% de la population mondiale. Ce virus, rarement dangereux pour le sujet immunocompétent, représente une réelle menace chez le patient immunodéprimé comme le transplanté d’organe. Après la primo-infection, le CMV diffuse dans tout l’organisme et alterne des phases de latence et de réactivation. Il consacre 20% de son génome à diverses stratégies d’échappement immunitaire.Les objectifs de notre travail sont de décrire dans une première partie 1- la variabilité de six gènes, codant quatre protéines immunomodulatrices (UL18, UL40, UL111a et US3) et deux protéines immunodominantes (IE1 et pp65), dans des souches de CMV directement séquencées à partir de sang total ou du LBA de patients infectés et immunodéprimés, 2- le mécanisme conduisant à cette variabilité 3- la répartition des souches virales dans le sang total et le LBA (compartimentation).La deuxième partie est consacrée à l’expression de la protéine immunomodulatrice pUL40.Nos travaux ont permis de confirmer l’existence d’un polymorphisme notable, supérieur à ce qui est déjà décrit. Des conséquences fonctionnelles pourraient en découler dans les protéines correspondantes. L’étude in silico de la variabilité du CMV met en lumière le rôle clé de la recombinaison comme mécanisme évolutif majeur. Nous n’avons pas mis en évidence de compartimentation des souches virales dans les échantillons analysés.Nos résultats préliminaires indiquent la faisabilité de la sur-expression de la protéine pUL40, permettant ultérieurement de mieux comprendre ses fonctions.